Electric switch



Oct. 15V, 1957 G, L, HELLSTRQM `-27,810,031

` 'YELECTRIC'SWITCH Filed oct. 2a, 1955 5 sheets-sheet 1 GEK@ Oct. 15,1957 G. L. HELLs'rRoM ELECTRIC 'SWITCH 5 Sheets-Sheet 2 Filedl Oct. 28,1955 ,Av1 E MN, @P \\\\\&4 1 .Il a

Oct. 15, 1957 G. L. HELLsTRoM 2,810,031

ELECTRIC swITcH Filed Oct. 28, 1955 5 Sheets-Sheet 3A "wm/wmf Oct. l5,1957 G. l.. HELLs'rRoM.r 2,810,031

" ELECTRIC -SWITCH Filed oct. 28, 1955 l 5 sheets-sheet 4 /d //9 /30INVENTOR.

Oct. 15, 1957 G, L. HELLsTRoM 2,810,031

V ELECTRIC SWITCH Filed Oct. 28, 1955 5 Sheets-Sheet 5 IN V EN TOR.

United States Patent O ELECTRIC SWITCH Gosta Ludvig Hellstrom,Stockholm, Sweden Application October 28, 1955, Serial No. 543,423

Claims priority, application Sweden November 26, 1954 14 claims. (cl.zoo- 67) My invention relates to electric switches.

An object of my invention is to provide an improved switch of simplifiedconstruction which `requires relatively few parts and can be readilyassembled.

Another object is to provide an improved switch which embodies a movableforce transmitting member for positively shifting a coupling member withwhich a movable Contact is associated, and, when such positive shiftingof the coupling member is terminated, completing the shifting of thecoupling member by imparting thereto angular momentum with the aid offorces developed by an overcenter spring.

A further object is to provide an improved switch operated by a thrustmember or push button in which the movable contact moves practicallyinstantaneously from its circuit closing to its circuit opening positionand vice versa irrespective of the rate at which the thrust member orpush button is moved to its depressed position.

A still further object is to provide an improved switch which embodies amovable force transmitting member for shifting a coupling member withwhich the movable contact is associated, the force transmitting memberhaving a pair of arms which serve to hold and retain an overcenterspring when it is deected to one side or the other of its line ofaction, the spring being held and retained in either of its stationaryend positions by that `arm which becomes subject to a lateral bendingforce developed by its deflection while the other arm transmits from thespring to the coupling member a force acting in the same generaldirection as the lateraly bending force, which insures that the movablecontact will always be at one or the other of its extreme end positions.

Further objects and advantages of my invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaims annexed to and forming a part of this specication.

For a better understanding of my invention, reference may be had to thefollowing description taken in connection with the accompanyingdrawings, in which:

Fig. l is a perspective view of an electric switch embodying theinvention; Fig. 2 is a top plan View, partly broken away and in section,of the switch shown in Fig. l; Fig. 3 is a vertical sectional View takenat line 3--3 of Fig. ll; Figs. 4 to 8 are perspective views of detailsor parts of the switch shown in Figs. 1, 2 and 3; Figs. 9 and l are planviews of the base and cover plate, respectively, of the switch shown inFigs. l, 2 and 3, the views being in directions from the joint betweenthe parts when assembled; Figs. 11, l2 and 13 are similar verticalsectional views illustrating the switch of Figs. l, 2 and 3 in closed,intermediate and open positions, respectively; Figs. 14 to 17 are viewsdiagrammatically illustrating the forces developed, by the spring of theswitch when the parts thereof are in diierent positions;` Figs. 18, 19and 20 are vertical views, partly in section, of an electric switchillustrating another embodiment of the invention, the figures beinggenerally like Figs. l1, 12 and 13 and illus- 2,810,031 Patented Oct.15, 1957 trating the switch in open, intermediate and closed positions,respectively; Fig. 2l is a vertical sectional view taken at line 21-21of Fig. 18; Figs. 22 and 23 are vertical views, partly in section, of anelectric switch illustrating a further embodiment of the invention, theligures being generally like Figs. 1l and 12 and illustrating the switchin a closed and intermediate position, respectively; and Fig. 24 is avertical sectional View taken at line 24-24 of Fig. 22.

AReferring to Figs. l and 2, I have shown my invention embodied in anelectric switch having a base 10V and cover 11 forming an outer shell orhousing 12, these parts being secured together by nuts 14 having hollowsleeve portions which are internally threaded to receive tighteningscrews 15. The cover 11 is formed with a central opening 16 throughwhich a member 17 extends exteriorly of the housing 12, the member 17serving as a thrust member for operating mechanism 18 to bring a movablecontact 19 into and out of engagement with a pair of stationary contacts20 adapted to be connected in an electrical circuit.

The stationary contacts 20, one of which is illustrated in Fig. 5, formparts of terminal members having apertured base portions 20a whichreceive threaded screws 20h. The base portion 20a of each terminalmember, except that part against which the head of screw 20c overlies,bears against and is clamped between surface areas of the base 10 andcover 11 of the housing 12. A ridge formed in the base 10 is notched at21, as illustrated in Figs. 2 and 9, to receive andhold edge portions ofthe contacts 2t). The cover 11 is notched at 22, as seen in Fig. l0, toreceive the opposite edge portions of the contacts 20 and clamp thelatter in place between the base 10 and cover 11 of the housing 12. Whenclamped in position in this manner, only the heads of the screws 20b andparts of the base portions V20a which,

the cover 11 being recessed at 23, as seen in Figs. 3 and Y 10, toreceive the outer ends ofthe screws 20b.

The movable contact 19, which is illustrated in Fig. 8, is of U-shapeand includes a pair of parallel arms which serve as contact fingers 19aand a connecting plate or base part 19b notched at 19e. The outer endsof the contact fingers 19a, which are enlarged and essentially circular,move into and out of intimate contact with the stationary contacts 20,as best seen in Figs. 3 and 11, the inwardly projecting ends of thecontacts 20 being bent and flared outwardly with respect to one another.

As best seen in Fig. 4, the thrust member 17, which in the preferredembodiment serves as a push button for manually operating the switch, isin the form of `a hollow rectangular shaped sleeve having a closed endand side walls 17a and 17b. The sidewalls 17b are longer than the sidewalls 17a and formed with raised portions 17c` at their outer ends whichserve as stops to limit the extent of outward movement of the member 17through the opening in the cover 11, as will be evident whenv referenceis made to Fig. 3. g

The mechanism 1liA interposed between the thrust member 17 and movablecontactv 19- includes an elongated helical spring 24, a multi-armedforce transmitting member 25 formed to hold and retain one end of thespring, and a bridge member 26 having a projection 26a arranged to`receive the opposite end of the spring, as best' shown in Fig; 7. Thebridge member' 26 is formed with arms having recesses 26h at each' sideof' the projection 26a in which diametrically opposite regions of thespring rest.

The force transmitting. member 25, which is in the form of a hollowvessel, is provided with notches or recesses 25a at the open end thereofin the opposing arms 25b and 25e, whichV are alternately adapted to` beengaged by' the ends 26e` of the bridge' arms when the' bridge member 26moves between closed and open positions of the switch, as will beexplained presently.

The mechanism 1S, which may be referred to as a spring compression andbow unit, is pivoted at its opposing ends to enable the forcetransmitting member 25, overcenter spring 24 and bridge member 215 toswing back and forth between the positions illustrated in Figs. 11 and13, the overcenter spring 24 in these positions being bowed in oppositedirections from the line of action or straight line position illustratedin Fig. 12. As seen in Figs. ll, 12 and 13, the thrust member 17 isformed with a ridge or knife-edge 17d at the inside thereof which isadapted to receive a notch or groove 25d formed at the closed end of thehollow force transmitting member 25.

As shown in Fig. 9, at the bottom of the base 11) is formed a U-shaperidge 27 and a pair of L-shape ridges 2S, the ridges being arranged toform a pair of elongated grooves 29 therebetween. The arms of theU-shape ridge 27 at their ends are beveled at 27a, as best shown inFigs. 9 and 1l. The sides of the shorter arms of the L-shape ridges 28are beveled at 28a as best shown in Figs. 9 and l2. The gap between thebeveled edges 27a and 23a, in a direction transverse to the parallelarms of the U-shape ridge 27, forms a groove 29 which is adapted toreceive the cross plate or base part 19e of the movable contact 19. Themovable contact 19 moves through an acute angle in the groove 29, theaxis about which such angular movement is effected being about a linepassing through the extreme bottom portion 19d of the base part 191: ofthe movable contact 19, as best seen in Fig. 3.

The bridge member 26 is formed with a slot 26d of X- shape, as bestshown in Fig. 7. The notchedpart 19C of the movable contact 19 forms asaddle which receives the recessed part 26d of the bridge member 26.Since the slots 26d is of X-shape, the bridge member 26 can moveangularly with respect to the base part 1915 of the movable contact 19.The angular movement of the bridge member 26 with respect to the Contactmember 19 is limited, such relative angular movement terminating when along side of the X-shape slot 26d, with angular movement being impartedto the bridge member 26, engages and contacts a side or face of the basepart 19h of the movable contact 19. It will now be understood that thebridge member 26 moves angularly about an axis 30, indicated by a dottedline in Fig. 8 which passes through the bottom of the notch 19C of themovable contact member 19. Also, the axis 30 about which the bridgemember 26 is angularly movable is nearer to the recessed regions 26bholding an end of the spring 24 than the axis at 19d about which themovable contact 19 is angularly movable.

The base and cover 11 of the housing 12, thrust member 17 and forcetransmitting member 25 are made of any suitable insulating material. Theterminal members, of which the stationary contacts form a part, and themovable contact 19 form electric conducting parts which are mounted onthe insulating parts in the manner described above. The spring 24 andbridge member 26 desirably are formed of metal.

In order to simplify the description, the force transmitting member willbe referred to hereinafter in the specification and also in the claimsas a force member, and the bridge member 26, which is movable betweenthe two positions illustrated in Figs. 11 and 13, respectively, will bereferred to as a part of a coupling member with which the movablecontact 19 is operatively associated.

The parts of the switch described above are shown in one stationaryposition in Figv 11. In such position, the stops 17e of the thrustmember 17 are functioning to limit outward movement thereof through theopening in the cover 11 and the spring 24 is under compression and bowedor deflected against the left-hand arm or side 25h of the force member25. Under these conditions an upward force P1 is exerted by the spring24 against the force member 25 at a region of the latter which is to theleft of the knife edge 17d. A downward force P2 is also exerted by thespring 24 against the bridge member 26 and movable contact 19 at aregion which is to the left of the positions at which these parts aresupported.

'Ihe upward force P1 is transmitted through the righthaud side or arm25C of the force member 25 and the right-hand arm of the bridge member26 to the movable Contact 19, such force being designated P3 in Fig. ll.The lower end of the spring 24 bears against and comes in intimatecontact with the bridge member 26 at a single region 31, thereby causingthe spring to be bent or bowed toward the left in Fig. 11. The left-handarm or side 25h of the force member 25 serves to support and maintainthe spring 24 in a definite position with no opportunity for the springto be distorted out of shape. Such deflection of the spring 24 developsa lateral upward force P4 which, together with the upward force P1,cooperates to exert a force to maintain the movable contact 19 in theleft-hand position shown in Fig. 11 at the same time that the upward andlateral forces P1 and P3, respectively, are effective to maintain therecess 25a in the right-hand arm 2SC of the force member 25 in intimatecontact with f and bearing against the right-hand arm of the bridgemember 26.

The thrust member 17 is depressed when it is desired to operate theswitch. When this occurs, the force member 25 in Fig. 11 is movedagainst the right-hand arm of the bridge member 26, thereby forcing thebridge member to be angularly moved in a clockwise direction and at thesame time imparting angular movement to the force member 25 toward theright about the knife edge or pivot point 17d.

When movement is imparted to the force member 25 toward the right fromthe position shown in Fig. l1, the left-hand arm or side ZSb thereofbears against the spring 24 to impart movement thereto, thereby causingthe spring to be moved toward its straight line position to assume amore straightened position. Such straightening of the spring 24 is alsoeffected by the bridge member 26 which, when being angularly moved in aclockwise direction in Fig. 11, raises or lifts the lower end of thespring 24 at the region 24a of the extreme bottom turn thereof.

When clockwise angular movement is initially imparted to the bridgemember 26 in Fig. 11, the contact member 19 remains stationary. Movementis imparted to the contact member 19 only after the bridge member 26 hasmoved through an acute angle equals to the angle measured between theconecting base part 19e of the contact member and a long side 26e of theX-shape slot 26d of the bridge member 26, as indicated in Fig. ll.

Since the bridge member 26 moves angularly about the axis 39, asindicated in Fig. 8, it will be apparent that the depth of the U-shapenotch 19t: at the closed end of the movable Contact 19 determines theposition of this axis. Since the contact member 19 in turn is angularlymovable about the axis 19d, as indicated in Figs. 3 and 11, it will beunderstood that the axis 3i) about which the bridge member 26 moves isnearer than the axis 19d of the contact member 19 to the region or place2612 at which the spring 24 acts on these parts. By virtue of thisrelationship of the contact member 19 and the bridge member 26, theforce P2 developed by the spring 24 in turn produces forces P5 and Pswhich effectively hold the contact member 19 in the extreme left-handposition shown in Fig. ll when clockwise angular movement is initiallyimparted to the bridge member 26. It is only after the bridge member 26has moved through the angle a in Fig. 1l, and the long side 26e of theX-shape slot 26a bears against a face of the bottom connecting part 19inof the movable contact19, that movement is imparted to the latter.

Fig. 12 illustrates the relative positions of the parts when the thrustmember 17 has been depressed sui'iciently to move the overcenter spring24 to its line of action and the forces developed by the spring andacting on the bridge member 26 and movable contact 19 are such thatthese parts are in a labile neutral position. Upon oontinued inwardmovement of the thrust member 17, the parts are positively moved towardthe right in Fig. 12, the force developed by the spring 24 against thebridge member 26 all the while producing a torque in a clockwisedirection on the latter which is of increasing magnitude. During suchmovement of the spring 24 from the straight line position in Fig. l2,the spring assumes a bowed or bent position opposite from thatillustrated in Fig. ll.

The bent spring 24 now acts against the right-hand arm or side 2SC ofthe force member 25, and a lateral force P7 is developed which also actson such right-hand arm 25e. As the force member 2S is moving toward theright in Fig. 13 and the lateral force P7 becomes increasingly greater,the recessed portion 25a in the righthand arm 25C eventually becomesineffective to hold the extreme end 26e of the right-hand arm of thebridge member 26 and the force member 25 becomes disengaged from theright-hand arm of the bridge member and moves angularly toward the rightto the position shown in Fig. 13.

As the spring 24 moves from the straight line position in Fig. l2 to thedeected position shown in Fig. 13, it `develops an upward force Ps atthe right-hand side of the knife edge 17d which also imparts angularmovement to the force member 2S toward the right. The spring 24 alsodevelops a downward force P10, indicated in Fig. 13, which impartsangular movement to the bridge member 26 in a clockwise direction. Thedoublearmed force member 25 and the bridge member k26 are supported atsuch a distance from` one another and are developed in such a mannerthat the lateral and upward forces P7 and Pa, respectively, which aredeveloped by the spring 24, are effectively transmitted through theleft-hand arm or side 25b of the force member to the left-hand arm ofthe bridge member 25 both by impact and by a force P9, thereby impartingan angular momentum to the bridge member 26 in a clockwise directionwhich is in addition to the movement imparted thereto by the downwardforce P10.

ln View of the foregoing, it will now be understood that as the partsor" the switch move from the position shown in Fig. ll past the neutralposition shown in Fig.

l2, the notch or recess 25a in the right-hand arm 25o` of the forcemember is in engagement with the eXtreme end 26C of the right arm of thebridge member 26. While these parts of force member 25 and bridge member26 are in engagement, the bridge member 26 and movable contact 19supported thereon are being angularly moved by a force transmitted fromthe right-hand arm 2SC of the force member to the right arm of thebridge member, such positive shifting of the bridge member and contactarm being effected independently of the spring 2dy while the latter isbeing moved to and past its labile neutral position.

When the overcenter spring 24 moves past its line of action or labileneutral position, the forces P7, Pa and Pio developed by the springbecome of increasingly greater magnitude. When the switch parts are in acertain position between the neutral position seen'in Fig. l2 and theposition shown in Fig. 13, the positive shifting of the bridge member 26by the force member 25 terminates due to the right arm of the bridgemember 26 becoming disengaged from the right-hand arm 25e of the forcemember. When this certain position of the switch parts is reached,angular movement is imparted to the bridge member 26 and movable contact19 solely by the forces developed by the spring 24, as explained above.The angular momentum imparted to the bridge member 26 by the forces P7,Ps, P9 and Pio,

of the force member 25 against the left arm of the bridge member 26, isof such magnitude that the angular movement of the bridge member 26 isaccelerated in the act of moving the contact fingers 19a of contact 19out of engagement with the stationary contacts 2t).

The aforementioned certain position of the switch parts, when thepositive shifting of the bridge member 26 by the force member 25 isterminated and such shifting is completed by the forces developed by thespring 24, is determined by the forces acting on the movable contact 19.These forces include the braking forces, contact pressure and otherfrictional forces acting on the movable contact 19.

An important advantage realized from a switch like that being describedand illustrated and embodying the principles of the invention is thatwhen tolerance limits are exceeded which would jeopardize dependableoperation of other switch constructions, the fact that such tolerancelimits are exceeded in switches constructed according to the inventionis not so material. This is so because the positive shifting of thebridge member 26 by the force member 25 continues until the increasinglygreater angular momentum given to the bridge member by the downwardforce P10, which is developed by the spring 24, imparts to the movablecontact 19 an angular velocity appreciably greater than the velocity atwhich the thrust member 17 is depressed. This increasingly greaterangular momentum, which acts on the movable Contact with a relativelyshort lever arm, receives a substantial boost by the impact of the forcemember 25 on the bridge member 26 as well as by the force transmitted tothe latter from the force member, so that the angular shifting of thebridge member 26 and movable contact 19 thereon is assured.

When the thrust member i7 in Fig. 13 is released and allowed to moveexteriorly of the shell orV housing 12 by the biasing action of thespring Z4, the force developed in the left-hand arm 25b of the forcemember continues to exert a pressure -against the left arm of the bridgemember 26. When the thrust member 17 in Fig. 13 reaches its outermostposition, as indicatedby the dotted line, the extreme outer endl of theleft-hand arm 25h of the force member rides over the eXtreme outer end26C of the left arm of the bridge member. When this occurs, the forcemember 25 swings to the right and the extreme outer end 26e of the leftarm of the bridge member enters the notch or recess 25a in the left-handarm 25b of the force member, whereupon the parts of the switch are in astationary position which is a mirror image of Fig. 11. In view of theforegoing, it will be evident that the gap or distance between therecesses 25a in the arms ZSb and 25s of the force member is greater thanthe gap be tween the extreme ends 26e of the bridge member 26, as bestseen in Fig. 12.

When the thrust member is again depressed and subsequently released, theparts of the switch move back to the position shown in Fig. ll and thecontact fingers 19a of the movable contact i9 are in engagement with thestationary contacts 20. In such return movement of the movable contact19, the forces P1, P2 and P4 developed by the spring 24 act in threedirections and cooperate with another to effect movement of the movablecontact 19. The spring 24, which is relatively Weak, enables the switchto be operated easily yand silently; and, since the forces developed bythe spring while under compression are transmitted through relativelyshort lever arms, it is possible to provide a switch like that describedand illustrated which is of small size and yet produces the necessaryforce to move the contact lingers 19a into engagement with thestationary contacts 20. By way of example and without limitation, aswitch like that described and illustrated has been constructed foroperating household vacuum cleaners of standard size in which thelength, width coupled with the impact force of the left-hand arm 251:and depth of the outer Shell are 1%, wie" and its,

respectively. The overall height of the switch, when the Vthrust member17 is not depressed, is 13716.

It will be seen that the force member 25, which is formed of insulatingmaterial, provides a partition between the stationary contacts 20 whenthe movable contact 19 moves into and out of engagement therewith, asbest seen in Fig. 2. The two relatively thin walls 25]c connecting thearms 25d and 25e form a space in which the spring 24 is positioned. Thegap between the side walls ZSf of the force member can be maderelatively large to provide a suitable shielding action between thestationary contacts 2i) at the instant the movable contact 19 becomesdisengaged therefrom. In this way, the distance between the stationarycontacts 20 can be made relatively small, especially in switches ofsmall size having a narrow width, without any danger of arcing betweenthem when the movable contact 19 is disengaged therefrom.

In Figs. 14 to 17 I have schematically illustrated the manner in whichthe forces are developed in the spring 24 and transmitted from thelatter and the force member 25 to the bridge member 26 upon which themovable contact 19 is carried. 1n Figs. 14 to 17 the left and right-handarms of the force member 25 are designated 25b and 25C and the recessesat the outer ends thereof are indicated at 25a. The force member 25 isformed with a pointed end 25e which is angularly movable in a groove 17eformed at the underside of the thrust member 17. In Figs. 14 to 17 thebridge Z6 is formed with arms having extreme end portions 26C. In Figs.14 and 15 the projection 26a on the bridge member 2.6 isdiagrammatically indicated, while in Figs. 16 and 17 the recesses 26h ateach side of the projection 26a are diagrammatically indicated.

In the diagrammatic views seen in Figs. 14 to 17 the movable contactpart 1917 and bridge member 26 move as a single unit. Hence, therelative angular movement effected between the movable contact 19 andbridge member 26, which is obtained in the manner described above andapparent in Figs. 11, 12 and 13, is not illustrated in the diagrammaticviews of Figs. 14 to 17 in order to make these views as simple aspossible.

In Figs. 14 to 17 the bridge member 26 is diagrammatically supported onthe movable contact member 19, only the bottom part 19h of which isshown. The part 1911 is angularly movable in a groove 29 formed in abase 11i which are diagrammatic representations of the correspondingparts seen best in Figs. 9 and 12.

Figs. 14 and 15 illustrate the development of the spring forces when theovercenter spring 24 is at the left and right-hand sides of the line ofaction or neutral labile position indicated at 24a. Fig. 14 illustratesthe upward force P1 developed by the spring 24 at the left of the lineof action 24a and the manner in which this force is transmitted throughthe right-hand arm 25e of the force member 2S and applied by the latterto the right arm of the bridge member 26, as indicated by the force P3.Fig. 15 illustrates the upward force Pa developed by the spring 24 atthe right of the line of action 24a and the manner in which this forceis transmitted through the left-hand arm 2515 of the force member 25 andapplied by the latter to the left arm of the bridge member 26, asindicated by the force P9.

Figs. 16 and 17 illustrate the way in which the bending and deecting ofthe spring 24 is promoted and the lateral forces developed by the latterwhich cooperate with the upward and downward forces developed by thespring. In Fig. 16 the eXtreme lower turn of the spring 24 engages thebridge member 26 at the single point 31 which promotes bending of thespring at the left of the line of action 24a, such bending of the springdeveloping the lateral force P4 which cooperates with the upward springforce P1 to increase the magnitude of the force Ps. In Fig. 17 theextreme lower turn of the spring 24 engages the bridge member 26 at thesingle point 31a,

which is directly opposite the point 31 in Fig. 16, thereby promotingbending of the spring at the right of the line of action 24a anddeveloping the lateral force P7 which cooperates with the upward springforce Pa to increase themagnitude of the force P9.

It has been explained above that, when the positive shifting of thebridge member 26 by the force member 25 is terminated, the shifting ofthe bridge member is completed by the angular momentum imparted to thelatter by forces developed by the spring 24. These forces developed bythe spring 24, which are transmitted directly to the bridge member andthrough the force member 25, become of increasingly greater magnitude asthe bending of the spring becomes more pronounced, thereby acceleratingthe angular movement of the bridge member 26. Even when the thrustmember 17 returns from the depressed position to the raised dotted lineposition in Fig. 13, the left-hand arm 25h of the force member 25continues to move angularly from the position shown in Fig. 13 to laposition which is the mirror image of the right-hand arm 25C of theforce member 25 in Fig. 11. In this way, the notch 25a in the left-handarm 25h of the force member 25 eventually receives and engages theextreme end 26C of the left arm of the bridge member, so that the forcemember 25 will again be effective to positively shift the bridge member26 when the thrust member 17 is depressed to move the movable contact 19to the left into engagement with the stationary contacts 211. Hence,even as the thrust member 17 moves exteriorly of the shell 12 afterbeing depressed, such outward movement enables the spring 24 to be bentto a greater degree which in turn develops a lateral force of greatermagnitude and like the force P4 in Fig. 11, for example, to insure agood contact pressure between the contact fingers 19a and stationarycontacts 2t) even when the parts are in a position of rest. The bridgemember 26 is embodied in the switch in such a manner that it will movefreely and enable the movable contact 19 to move practicallyinstantaneously from its circuit closing position to its circuit openingposition and vice versa irrespective of the rate at which the thrustmember 17 is moved to its depressed position. This is characteristic ofthe switch because the spring 24 is compressed and it moves beyond theline of action or labile neutral position before the movable contact 19becomes disengaged from the stationary contacts 20. It is only after thespring passes through and beyond the labile neutral position that theforces developed by the spring begin to act in such directions that theseparation of the contacts is effected.

In view of the foregoing, it will now be understood that an improvedswitch has been provided of simplified construction which requiresrelatively few parts and can be readily assembled. The parts formed ofinsulating material can be formed with simple tools and do not requireso-called undercutting The switch illustrated in Figs. 1 to 13 isextremely dependable in operation and highly resistant to wear, therelationship of the parts being such that errors in tolerance do notadversely affect switch operation and its durability.

Figs. 18 to 21 illustrate another embodiment of the invention in whichparts similar to those shown in the first described embodiment aredesignated by the same reference numerals to which one hundred has beenadded. In Figs. 18 to 21 the housing or shell includes a base and cover111 which are removably secured together in any suitable manner, as inthe embodiment of Figs. 1 to 13, for example. The cover 111 is formedwith a central opening 116 through which a thrust member 117 extendsexteriorly of the housing, the thrust member having a projection 117C tolimit outward movement thereof. The member 117 serves as la push buttonfor operating mechanism 118 to bring a U-shape and out of engagementwith a pair of stationary con- 9 facts 120 which form part of terminalmembers 120:1 adapted to be connected in an electrical circuit.

The mechanism 118 interposed between the thrust member 117 and movablecontact 119 includes an elongated helical spring 124, a multi-armedforce member 125 arranged to hold land retain one end of the spring, anda bridge member 126 having a projection 126:1 arranged to receive theopposite end of the spring. The force member 2.5, which is in the formof a hollow vessel, is provided with notches or recesses 12Sa at theopen end thereof in the opposing arms 12517 and 125e, which arealternately ladapted to be engaged by the ends 126e of the bridge armswhen the bridge member 126 moves between closed and open positions ofthe switch, as in the first described embodiment.

As seen in Figs. 18, 19 and 20, the force member 125 is formed with apointed end 125e which is angularly movable in a groove 117e formed atthe underside of the thrust member 117. The base 110 is formed with agroove 129 which is Iadapted to receive the` cross connection or basepart 119b of the movable contact 119. The bridge member 126 is formedwith a slot 126d of inverted V-shape which tits in a notched part 119eof the closed end 11% of the U-shape movable contact 119, as best shownin Figs. 19 and 20. As in the first described embodiment, the opposingedges of slot 126d diverge from one another so that the bridge member126 can move angularly with respect to the base part 119b of the movablecontact 119.

The bridge member 126 moves angularly about an axis 131i, indicated by adotted line in Fig. 21, which passes through the bottom of the notch119e of the movable contact member119. The axis 130 about which thebridge member 126 is angularly movable is nearer to the bottom end ofthe spring 124 than the axis at 119d about which the movable contact 119is angularly movable. When angular movement is initially imparted to thebridge member 126 from a position of rest, the contact member 119remains stationary. Movement is imparted to the contact member 119 onlyafter the bridge member 126 has moved through an acute angle a equal tothe angle measured between the connecting base part 119b of the contactmember 119 and an edge of the V- shape slot 126:1 of the bridge member126, as indicated in Fig. 18.

The operation of the switch illustrated in Figs. 18 to 2l is essentiallythe same as that of the switch shown in Figs. 1 to 13 and describedabove and will not needlessly be repeated here. The different forcesproducedV in the operation of the modification of the invention shown inFigs. 18 to 21 are like those seen in Figs. 11 and 13 and are designatedby the same reference letters, it being further understood that theforce diagrams of Figs. 14 to 17 are applicable equally well to theembodiment of Figs. 18 to 21 as to the tirst described embodiment ofFigs. l to 13.

1n Figs. 22, 23 and 24 I have shown another embodiment in which partssimilar to those shown in the embodiments described above are designatedby the same reference numerals to which two hundred (200) has beenadded. Figs. 22, 23 and 24 illustrate a shell or housing 212 of a switchhaving a base 210 and a cover 211 formed with an opening 216 throughwhich extends a thrust member 2,17 having projections 217e` to limitoutward movement thereof.

The underside of the thrust member 217 is formed with a recess 217e toreceive the pointed end 225e of a force member 225 which is in the formof a bow and provided with arms 225i: and 225C having notched orrecessed ends 225a. The notches or recesses 22511 are adapted to a1-ternately engage the extreme ends 226e of the arms of a bridge member226 which is pivoted at 226g in an opening 235 formed at the bottom partof a wall member 236 projecting inwardly of the housing 212 from thebase 210.

The wall member 236 serves as a pivot point for a movable contact 219comprising a pair of yspaced apart contact tingers 219e which areparallel to one another and upon which a slide member 237 is movablelength wiseof and between the contact fingers. The slide member 237 isof U-shape and receives the lower end of the spring 224. The bridgemember 226 is formed with pusher arms 226i which are of U-shape andperpendicular to the main bridge arms and serve to limit endwisemovement of the slide member 237 on the movable contact member 219.

ln the position illustrated in Fig. 22, in which the movable contact 219is in engagement with the stationary contacts 220, the forces developedby the spring 224 and right-hand arm 225C of the force member 225 aresimil-ar to the forces developed and identied in Fig. 11 of the irstdescribed embodiment. In Fig. 22 the downward spring force, similar tothe force P2 in Fig. 13, is acting against the left arm of the bridgemember 226 through the slide member 237, left-hand end of the movablecontact 219 and left-hand pusher arm 226f of the bridge member 226.

As the force member 225 positively shifts the bridge member 226 from theposition shown in Fig. 22 to the position shown in Fig. 23, the spring224 moves toward its labile neutral position, the left-hand pusher arm226]c vof the bridge member positively moving the slide member 237during this period of movement of the switch parts. When the spring 224moves through and beyond its labile neutral position, the forcesdeveloped by the spring 224 and force member 225 are essentially thesame as those developed by the corresponding parts in the rst describedembodiment and identified in Fig. 13. After the spring 224 moves throughand beyond its labile neutral position,

the slide member 237 moves to a position at the right- Y hand end of themovable contact 219. When the thrust member 217 moves outwardly of theshell or housing of the switch, the parts of the embodiment beingdescribed assume a position which is a mirror image of the relativeposition of the parts shown in Fig. 22. A

In Figs. 22 to 24 the movable contact 219 pivots about a region which isnearer to the lower end of the spring 224 than the region about whichthe bridge member 226 pivots. It will be observed that in the embodimentof Figs. 22 to 24 no relative angular movement is effected l between themovable contact 21.9 and the bridge member 226. In other respects,however, the operation of the embodiment of Figs. 22 to 24 isessentially the same as that of the embodiments illustrated anddescribed above.

Although I have shown and described particular embodiments of myinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from the spiritand scope of the invention. For example, the thrust member and for-cemember may be arranged in such a manner that the force member isangularly movable about two spaced apart pivot regions which are asubstantial distance from one another and symmetrically disposed withrespect to the thrust member, an arrangement which may be desirableunder certain conditions, in order to make certain that the shifting ofthe bridge member to its end position is completed before the lastincrement of angular movement of the force member is effected from theposition shown in Fig. 13, for example, to a position which is a mirrorimage of the switch parts illustrated in Fig. 11. I, therefore, aim inthe following claims to cover all such modications and changes as fallwithin the true spirit and scope of the invention.

What is claimed is:

l. An electric switch comprising a movable contact, a coupling membermovable between two positions, said coupling member including a bridgehaving two arms and with which said movable contact is operativelyassociated, a movable force member having a pair of arms, one of thearms of said force member having a part adapted to Y 11 Y Y be engagedby a part of one arm of said bridge and the other arm of said forcemember having a part adapted to be engaged by a part of the other arm ofsaid bridge, a thrust member movable between first and second positions,means comprising said force member for shifting said coupling memberback and forth between its two positions responsive to repeated movementof said thrust member from its first to its second position, the partsof the arms of said force member alternatively engaging the parts of thearms of said bridge upon successive movements of said thrust member fromits iirst to its second position, and the gap or distance between theparts of the arms of said force member being greater than the gap ordistance between the parts of the arms of said bridge adapted to beengaged alternatively by the parts of the arms of said force member.

2. An electric switch comprising a movable contact, a coupling membermovable between two positions, said coupling member including a bridgehaving two arms and with which said movable contact is Voperativelyassociated, a movable force member having a pair of arms, one of thearms of said force member having a part adapted to be engaged by a partof one arm of said bridge and the other arm of said force member havinga part adapted to be engaged by a part of the other arm of said bridge,a thrust member movable between irst and second positions, meanscomprising said force meinber for shifting said coupling member back andforth between its two positions responsive to repeated movement of saidthrust member from its first to its second position, the parts of thearms of said force member alternatively engaging the parts of the armsof said bridge upon successive movements of said thrust member from itsfirst to its second position, each arm of said force member, after saidbridge has been shifted in one direction by the other arm of said forcemember responsive to movement of said thrust member from its first toits second position, being movable in the same one direction toward saidbridge to bring the part associated therewith into engagement with thepart of the arm of said bridge with which it is adapted to cooperateresponsive to return movement of said thrust member from its secondposition toward its lirst position, so that said force member will beoperable to shift said coupling member in the opposite direction fromsaid one direction responsive to the next succeeding movement of saidthrust member from its first to its second position.

3. An electric switch comprising stationary and movable contacts, acoupling member angulaily movable between two positions and with whichsaid movable Contact is operatively associated, a force member movablebetween two position-s,-said force member having a pair of arms, athrust member movable between first and second positions, meanscomprising said force member for shifting said coupling member back andforth between its two positions responsiveV to repeated movement of saidthrust member from its first to its second position, said lastmentioncdmeans including an overcenter spring between said force and couplingmembers for biasing said thrust member to its first position andalternatively retaining said force and coupling members at one and theother of their two positions at opposite sides of the line of action ofthe spring, means including said force member for imparting angularmomentum to said coupling member responsive to a torce developed by saidspring when the latter moves through its line of action from one to theother side thereof, such angular momentum imparted to said couplingmember when said spring moves from one to the other side of its line ofaction being effective to move said movable contact into engagement withsaid stationary contact, each arm of said force member, when the latteris in one or the other of its two positions, serving to supportsaidspring while being deected from its line of action, and said movablecontact being urged to move as far as possible, while said spring isdeilected from its line of action toward one arm of said force member,responsive to forceY transmitted from said spring through the other armof said force member.

4. An electric switch comprising a movable Contact, a coupling membermovable between two positions and with which said movable contact isoperatively associated, a movable force member having a pair of arms, athrust member movable between first and second positions, meanscomprising said force member for shifting said coupling member back andforth between its two positions responsive to repeated movement of saidthrust member from its lirst to its second position, said last-mentionedmeans including a spring retained between said force member and couplingmember which biases said thrust member tcits first position, saidcoupling member including a bridge which is movable therewith andimparts movement to said contact, said bridge being eiective to imp-artmovement to said Contact only after movement has been imparted theretofor an interval of time responsive to shifting of said coupling memberfrom a position of rest by said force member.

5. A switch as set forth in claim 4 in which said spring acts against aplace of said coupling member, said movable contact comprising a memberangularly movable about a rst axis and said bridge being angularlymovable about a second axis which is nearer to the place at which saidspring acts than said first axis, said contact member, during theinterval of time said bridge is ineffective to impart movement thereto,being retained in a position of rest responsive to the action of saidspring on the part of said Contact member between said irs't and secondaxes.

6. A switch as set forth in claim 4 in which said contact comprises amember formed with a notch, and said bridge is formed with a slot inwhich the opposing edges diverge from one another, the notched portionof said contact member receiving and holding the slotted part of saidbridge.

7. A switch as set forth in claim 4 including structure providing asupport, said contact comprising a member which is angularly movableabout the support and said ridge member including a part resting on andangularly movable about a region of said contact member, said region,when the switch is positioned with said bridge member directly beneathsaid force member, being at a level at least as high as the support forsaid contact member.

8. A switch as set forth in claim 4 in which said contact comprises amember which is angularly movable, said member including a partextending lengthwise of the axis about which it moves and two contactfingers at opposite ends of said part which are formed integraltherewith, said contact fingers projecting radially from said axis atthe same side thereof as said part.

9. A switch as set forth in claim i in which said force member ispivotally movable on said thrust member, one of said members havin T agrooved part and the other of said members having a part fitting intoand angularly movable in such grooved part.

10. A switch as set forth in claim l which includes a wall part havingan opening, said thrust member extending through such opening andserving as a push button, such push button being of annular form havinga closed outer end and four walls extending inwardly therefrom throughthe opening, two of said walls being shorter than the other two wallswhich are disposed in planes essentially parallel to the plane ofmovement of the arms of said force member.

ll. An electric switch comprising a movable contact, a coupling memberangularly movable between two position-s and with which saidpmovablecontact is operatively associated, said coupling member including abridge, a movable force member having a pair of arms, a thrust membermovable between first and second positions, means comprising said forcemember for shifting said coupling member back and forth between its twopositions responsive to repeated movement of said thrust member from itsrst to its second position, said last-mentioned means including springmeans which biases said thrust member to its rst position andconstitutes the only means for retaining said thrust member, forcemember, bridge and contact in position with respect to one another whenthe parts just mentioned are at rest or movement is imparted thereto.

12. A switch as set forth in claim l1 which includes a two-part shell orhousing and means for removably connecting said parts, said spring meanscomprising a single elongated coil spring of helical form which, inaddition to said removable connecting means for said twopart shell,constitutes the only means for retaining said thrust member, forcemember, bridge and contact in position with respect to one another insaid shell when the parts just mentioned are at rest orpmovement isimparted thereto.

13. An electric switch comprising a pair of stationary contacts and amovable contact adapted to be brought into and out of engagementtherewith, a coupling member movable between two positions and withwhich said movable contact is operatively associated, a movable forcemember, a thrust member movable between rst and second positions, meanscomprising said force member for shifting said coupling member back andforth between its two positions responsive to repeated movement of saidthrust member from its first to its second position, said force memberbeing formed of insulating material and being disposed between saidstationary contacts to provide an insulating partition therebetween,especially when said movable contact becomes disengaged from saidstationary contacts, to reduce the likelihood of a disruptive dischargetherebetween.

14. A switch as set forth in claim 12 which comprises stationarycontacts cooperating with said movable contact, said stationary contactsbeing clamped in position between the two parts of said shell and havingterminal portions disposed exteriorly of said shell, and fastening meansfor said terminal portions adapted to make electrical connectionsthereto.

References Cited in the le of this patent UNITED STATES PATENTS1,997,209 Douglas Apr. 9, 1935 2,255,115 Helle Sept. 9, 1941 2,295,484Krieger Sept. 8, 1942 2,383,546 Hallander Aug. 28, 1945 2,529,970 SchmidNov. 14, 1950

